The present invention relates a vacuum processing apparatus including a plurality of processing chambers, which are provided with processing devices for effecting predetermined processing on an internally arranged target object to be processed under a predetermined pressure and can achieve predetermined internal pressures.
Semiconductor devices such as a semiconductor memory, a TFT for a liquid crystal display and a MPU are produced by effecting several kinds of processing on a substrate (i.e., an object to be processed) in a predetermined order. For example, the substrate is subjected to (1) processing of forming a film of a predetermined material on the substrate by a PVD method such as a sputtering vapor deposition method or an ion plating method, or a CVD method such as a plasma CVD method, (2) etching for removing a predetermined material from the substrate by a dry etching method such as an ECR plasma etching method, and (3) processing of implanting predetermined ions into the substrate by a doping method such as a plasma doping method. These film formation, dry etching and doping are usually performed under a pressure lower than an atmospheric pressure.
Therefore, a vacuum processing apparatus for effecting such processing is provided with a processing chamber in which a predetermined pressure can be achieved. The processing chamber is provided with a processing device for effecting predetermined processing on the substrate disposed in the chamber.
For effecting two or more kinds of processing on the same substrate, a plurality of vacuum processing apparatuses each provided with, e.g., only one processing chamber are prepared, and these vacuum processing apparatuses are used to effect successively the several kinds of predetermined processing on the substrate.
For effecting the several kinds of processing on the same substrate, the substrate which is subjected to predetermined processing in a certain vacuum processing apparatus is transferred to another vacuum processing apparatus for the next processing. During this transfer, the substrate is exposed to an atmosphere so that the substrate may be polluted with dust adhering onto the substrate or due to oxidization of the substrate. Particularly, in manufacturing processes of semiconductor devices, it is especially necessary to avoid mixing of impurities such as dust, and therefore the vacuum processing apparatuses are usually disposed in a clean room. However, it may be difficult to prevent pollution of the substrate even in the clean room. Therefore, pretreatment such as cleaning of the substrate prior to processing must be done that requires time and efforts, resulting in low efficiency.
For improving productivity by performing the several kinds of processing in a predetermined order, such a vacuum processing apparatus has already been proposed that is provided with a plurality of chambers for suppressing adhesion of dust or the like to the substrate and pollution of the substrate.
FIG. 8 shows a schematic plan of an example of a vacuum processing apparatus provided with a plurality of processing chambers.
The vacuum processing apparatus shown in FIG. 8 includes five chambers Ci, C1, C2, C3 and Co, in which predetermined pressures can be achieved, respectively. These five chambers are connected together in series via gate valves V2, V3, V4 and V5. This vacuum processing apparatus is called a vacuum processing apparatus of an in-line type.
The chambers C1, C2 and C3 are provided with processing devices (not shown), respectively. The chambers C1, C2 and C3 are provided for effecting predetermined processing on a substrate (an object to be processed or a target object) disposed therein by the processing devices. Thus, the vacuum processing apparatus includes three processing chambers.
Among the five chambers connected in series, the chamber Ci on one end is provided with a valve V1 for transferring the substrate into the chamber Ci through it. The chamber Ci serves as an inlet chamber for the substrate. The chamber Co on the other end among the five chambers is provided with a valve V6, through which the substrate in the chamber Co can be externally discharged. The chamber Co serves as a discharging or outlet chamber for the target object.
In the vacuum processing apparatus of the in-line type, the substrate is transferred into the inlet chamber Ci, then is moved through processing chambers C1, C2 and C3, and is discharged from the outlet chamber Co. The substrate is usually held on a tray, and is transferred between the chambers by moving the tray. In each processing chamber, predetermined processing is effected on the substrate transferred thereinto so that a series of processing can be continuously effected on the substrate. Since the substrate is successively transferred through the chambers kept at low gas pressures, adhesion of dust or the like onto the substrate as well as pollution of the substrate can be suppressed more effectively than the case where similar processing is performed in three vacuum processing apparatuses each provided with only one processing chamber as described before. Further, several kinds of processing can be efficiently effected on the substrate.
However, the vacuum processing device of the in-line type suffers from the following three problems (1)-(3).
(1) The tray holding the substrate is transferred into the respective chambers together with the substrate, and is subjected to the predetermined processing together with the substrate. Therefore, in the step of, e.g., forming a film on the substrate, the film is also formed on the tray. Thereby, much dust is produced from the tray, and pollutes the substrate.
(2) When maintenance work is to be performed on one of the processing chambers or one of the processing devices provided for them, or when one of the processing devices provided for the processing chambers has a trouble, the whole functions of the vacuum processing apparatus stop because the plurality of processing chambers are coupled in series.
(3) If a large number of processing chambers are coupled for continuously performing many kinds of processing, a large area is required for installing the whole vacuum processing apparatus. As already described, the vacuum processing apparatus is usually arranged in a clean room, which requires high costs per unit area (construction, maintenance and other costs). Therefore, increase in installation areas of the vacuum processing apparatus results in increase in processing costs of each substrate. Further, it may be impossible to install the vacuum processing apparatus, which is formed of the many processing chambers coupled in one row, in an existing clean room because it is lengthy, and requires a large installation area.
For overcoming the problems of the vacuum processing apparatus of the in-line type, a vacuum processing apparatus shown in FIGS. 9(A) and 9(B) is already proposed. FIG. 9(A) is a schematic plan of the vacuum processing apparatus, and FIG. 9(B) is a schematic cross section taken along line Xxe2x80x94X in FIG. 9(A).
The vacuum processing apparatus shown in FIGS. 9(A) and 9(B) includes eight chambers C1, C2, C3, C4, C5, C6, Ci and Co, where predetermined inner pressures can be attained. These chambers are disposed around a central chamber Cc, and are connected to the central chamber Cc via gate valves, respectively. The central chamber Cc can likewise attain a predetermined inner pressure.
Chambers C1-C6 are processing chambers provided with processing devices (not shown), respectively. The chamber Ci is an inlet chamber, and the chamber Co is an outlet chamber.
In the central chamber Cc, there is arranged a robot R which can transfer a substrate between the chamber Cc and each of the chambers C1-C6, Ci and Co.
In this vacuum processing apparatus, the substrate can be transferred to each of the processing chambers via the central chamber so that predetermined processing can be successively effected on the substrate in the respective processing chambers. A substrate holder may be arranged in each processing chamber. This structure can eliminate a substrate holding tray, which is employed in the vacuum processing apparatus of the in-line type for substrate transfer, and is transferred together with the substrate into each processing chamber. Therefore, generation of dust can be suppressed, and thereby pollution of the substrate can also be suppressed. Even when one of the processing chambers cannot be used due to maintenance work or trouble, processing to be performed in the unusable chamber can be performed in another processing chamber so that stoppage of all the functions of the vacuum processing apparatus can be avoided.
The vacuum processing apparatus shown in FIGS. 9(A) and 9(B), however, requires a large installation area for providing many processing chambers, similarly to the vacuum processing apparatus of the in-line type already described. In particular, for effecting several kinds of processing on a substrate of a relatively large area, each processing chamber must have a large size corresponding to the substrate size, and thereby the central chamber connected to the plurality of processing chambers must have a large size so that the whole installation area becomes large leading to increase in substrate processing costs.
For overcoming the above problems, Japanese Laid-Open Patent Publication No. 10-55972 proposed a vacuum processing apparatus shown in FIGS. 10(A) and 10(B). FIG. 10(A) is a schematic plan of the vacuum processing apparatus, and FIG. 10(B) is a schematic cross section of the vacuum processing apparatus taken along line Xxe2x80x94X in FIG. 10(A).
The vacuum processing apparatus shown in FIGS. 10(A) and 10(B) includes processing chambers C1-C8 as well as the inlet chamber Ci and the outlet chamber Co. These chambers are disposed around the central chamber Cc, and each is connected to the central chamber Cc via a gate valve. The robot R is disposed in the central chamber Cc for transferring a substrate.
The vacuum processing apparatus has a two-level structure. On the first level (i.e., lower level), the processing chambers C1, C3, C5 and C7 are disposed. On the second level (i.e., upper level), the processing chambers C2, C4, C6 and C8 are disposed. The processing chambers C2, C4, C6 and C8 on the second level overlap with the processing chambers C1, C3, C5 and C7 on the first level, respectively.
The vacuum processing apparatus shown in FIGS. 10(A) and 10(B) can perform several kinds of processing similarly to the vacuum processing apparatus shown in FIGS. 9(A) and 9(B). The vacuum processing apparatus shown in FIGS. 10(A) and 10(B) has the same advantages as the vacuum processing apparatus shown in FIGS. 9(A) and 9(B). Further, the vacuum processing apparatus shown in FIGS. 10(A) and 10(B) can increase the number of processing chambers without increasing the installation area, as compared with the vacuum processing apparatus of the single level structure in FIGS. 9(A) and 9(B), because the vacuum processing apparatus shown in FIGS. 10(A) and 10(B) has the two-level structure. Therefore, substrate processing costs can be reduced.
The vacuum processing apparatus, which is taught by Japanese Laid-Open Patent Publication No. 10-55972 and is shown in FIGS. 10(A) and 10(B), suffers from the following problems (4) and (5).
(4) The processing chamber (e.g., processing chamber C2) disposed on the upper second level substantially completely overlaps with the processing chamber (e.g., processing chamber C1) disposed on the lower first level. Therefore, the processing chamber disposed on the upper second level is not provided at its bottom portion with a sufficient space for arranging another instrument, device or the like. The processing chamber may be provided at its bottom portion with a lifting device which can vertically move the substrate holder for transferring the substrate to and from the robot R in the processing chamber. The processing chamber arranged on the lower first level can be provided at its bottom portion with the lifting device having a simple lifting mechanism, but the processing chamber disposed on the upper second level cannot be provided at its bottom portion with the lifting device having a simple lifting mechanism. For the processing chamber disposed on the upper second level, therefore, a lifting device to vertically move the holder must be disposed on the side portion of the chamber. This complicates the mechanism of the lifting device leading to higher costs.
(5) The processing chambers (lower processing chambers). disposed on the lower first.level (e.g., the processing chamber C1) substantially overlap with the processing chambers (upper processing chambers) disposed on the upper second level (e.g., processing chamber C2). Therefore, the lower processing chamber is not provided at its top portion with a sufficient space for arranging another instrument, device or the like. In the top portion of the processing chamber, there may be disposed a part or the whole of the processing device for effecting predetermined processing on the substrate disposed in the chamber. The processing chamber may be provided at its top portion with a lid for performing maintenance work such as cleaning in the chamber.
It is preferable that the lid for the maintenance work is arranged at the top portion of the processing chamber for convenience of the work. However, if the processing chamber on the lower level were provided at its top portion with the lid, it would be impossible to open this lid due to existence of the processing chamber on the upper level. For opening the lid, it is necessary to move either the upper or lower processing chamber overlapping with the other by a long distance to a position where these chambers do not overlap with each other. For this, the upper or lower processing chamber must be. coupled to the central chamber via a complicated and expensive mechanism including, e.g., a rail, a pivot arm and a hinge. This results in high costs.
For opening the lid, the upper or lower processing chamber must be moved to an appropriate space (i.e., maintenance space) radially outside the processing chamber. For ensuring this maintenance space, the vacuum processing apparatus shown in FIGS. 10(A) and 10(B) requires a space larger than its projected area. Practically, the installation space of the vacuum processing apparatus shown in FIGS. 10(A) and 10(B) cannot be significantly reduced from that of the vacuum processing apparatus shown in FIGS. 9(A) and 9(B).
Accordingly, an object of the invention is to provide a vacuum processing apparatus including a plurality of processing chambers, which are provided with processing devices for effecting predetermined processing on a target object, can achieve predetermined internal pressures, and can accommodate the target object for effecting predetermined processing under the predetermined pressures, respectively. More specifically, the object of the invention is to provide the vacuum processing apparatus, in which a substantial installation area is smaller than that of a conventional vacuum processing apparatus having the plurality of processing chambers of the same size and the same number, and easy maintenance of the apparatus can be achieved.
For achieving the above object, the invention provides a vacuum processing apparatus including a plurality of processing chambers provided with processing devices for effecting predetermined processing on a target object to be processed, being capable of achieving predetermined internal pressures, and being capable of accommodating the target object for effecting the predetermined processing under the predetermined pressures, wherein
the plurality of processing chambers are arranged around a central chamber provided for object transfer and being capable of achieving a predetermined inner pressure, and are connected with the central chamber; and
the plurality of processing chambers are disposed on two or more vertically different levels, and each of the processing chambers and a processing chamber neighboring thereto in the circumferential direction of the central chamber are disposed on different levels, respectively, and overlap only partially with each other.